CONTROLS ON MICROBIAL PROCESSING OF DISSOLVED ORGANIC MATTER IN BOREAL FOREST STREAMS DRAINING WATERSHEDS UNDERLAIN WITH DISCONTINUOUS PERMAFROST
In the boreal forest, permafrost thaw is resulting in changes in vegetation and deepening of watershed flowpaths. Caribou-Poker Creeks Research Watershed (CPCRW); (50 km NE Fairbanks, AK, USA) contains sub-catchments underlain with varying permafrost extents (4-53% cover), providing the opportunity to study how permafrost extent affects water chemistry and nutrient cycling. We measured nitrogen (N), phosphorus (P), and carbon processing ectoenzyme activity along a continuum of springs, headwater, and higher order streams, and related ectoenzyme activity to organic and inorganic nutrient and dissolved organic carbon concentrations. Relating ectoenzyme activity to water chemistry explained how variation in inorganic and organic N and P and carbon availability control microbial investment towards organic nutrient and carbon acquisition, elucidating what resources are limiting microbial processing of DOM. Water chemistry data at CPCRW indicates that P is likely limited. Preliminary ectoenzyme data supports this, with relatively high P processing ectoenzyme activity across water sources. P processing ectoenzyme activity was negatively correlated to soluble reactive P and positively correlated to nitrate concentrations, suggesting that inorganic nutrients are important in controlling organic matter utilization.
Marie Schmidt (Primary Presenter/Author), University of Alaska Fairbanks, email@example.com;
Jeremy Jones (Co-Presenter/Co-Author), University of Alaska Fairbanks, firstname.lastname@example.org;